4 
I. NAGAI : 
to obtain the flavone from the anthocyanin of Antirrhinum by the same 
manner jnst quoted, but failed. She obtained only a yellowish brown solu¬ 
tion. 
Harrow and Gies (1919) 1 observed the reversible colour changes in the 
solution of flavone and anthocyanin isolated from the flower of tulips by means 
of nascent hydrogen and hydrogen peroxide respectively. 
The writer observed that the coloured reduction product of quercetin, 
myricetin, apigenin, and luteolin yielded a yellow solution when treated with 
lijxlrogen peroxide and in the case of the first two, the original colours were 
resumed by further reduction by means of hydrochloric acid and magnesium 
powder. If, however, the reduced, coloured solutions were decolourized by 
an excess of hydrogen peroxide, the yellow solution so obtained failed to 
recover the reddish hue by reduction. 
The aqueous extract of the violet anthocyanin from the perigone leaf of 
Iris Kœmpferi and the purple one from the leaf of Perilla nankinensis were 
also changed to yellow by hydrogen peroxide and they yielded again an 
orange red colour by reduction but no initial bluish hue. 
The red colour of the reduced solution of quercetin, quercitrin, and 
myricetin were converted to yellow by the addition of an aqueous solution of 
potassium permanganate, and the further addition finally rendered the solution 
completely colourless. 
The mode of action of hydrogen peroxide and the oxidizing enzyme on 
anthocyanin was studied colorimetrically. One of the difficulties here met 
with, was the change in hue as the action proceeded. It is naturally to be 
expected that yellow colour should increase in depth as the anthocyanin is 
converted to a flavone like substance and at the point where fifty per cent of 
anthocyanin is converted to the yellow substance, the colour of the solution 
becomes about half way between red and yellow, namely orange. When 
violet anthocyanin is used, the change in hue is so distinct that no direct 
comparison can be made with the standard colour. With red and orange-red 
ones, however, the change in hue does not take place in a marked degree up 
to a certain point, hence the approximate measurement becomes possible. 
1. Hahkow. B. and Gies, W. J., Experimental Studies on Plant Pigments. Columbia Univ. 
Proc. Soc. Exp. Biol. Med. 16:8, 1918, Review in Chem. Abstract. 13: 2695, 1919. 
